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georgezhang11gregkh
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VMCI: resource object implementation.
VMCI resource tracks all used resources within the vmci code. Signed-off-by: George Zhang <[email protected]> Acked-by: Andy king <[email protected]> Acked-by: Dmitry Torokhov <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>
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‎drivers/misc/vmw_vmci/vmci_resource.c‎

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/*
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* VMware VMCI Driver
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*
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* Copyright (C) 2012 VMware, Inc. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation version 2 and no later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#include <linux/vmw_vmci_defs.h>
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#include <linux/hash.h>
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#include <linux/types.h>
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#include <linux/rculist.h>
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#include "vmci_resource.h"
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#include "vmci_driver.h"
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#define VMCI_RESOURCE_HASH_BITS 7
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#define VMCI_RESOURCE_HASH_BUCKETS (1 << VMCI_RESOURCE_HASH_BITS)
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struct vmci_hash_table {
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spinlock_t lock;
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struct hlist_head entries[VMCI_RESOURCE_HASH_BUCKETS];
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};
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static struct vmci_hash_table vmci_resource_table = {
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.lock = __SPIN_LOCK_UNLOCKED(vmci_resource_table.lock),
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};
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static unsigned int vmci_resource_hash(struct vmci_handle handle)
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{
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return hash_32(handle.resource, VMCI_RESOURCE_HASH_BITS);
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}
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/*
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* Gets a resource (if one exists) matching given handle from the hash table.
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*/
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static struct vmci_resource *vmci_resource_lookup(struct vmci_handle handle,
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enum vmci_resource_type type)
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{
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struct vmci_resource *r, *resource = NULL;
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struct hlist_node *node;
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unsigned int idx = vmci_resource_hash(handle);
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rcu_read_lock();
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hlist_for_each_entry_rcu(r, node,
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&vmci_resource_table.entries[idx], node) {
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u32 cid = r->handle.context;
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u32 rid = r->handle.resource;
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if (r->type == type &&
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rid == handle.resource &&
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(cid == handle.context || cid == VMCI_INVALID_ID)) {
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resource = r;
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break;
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}
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}
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rcu_read_unlock();
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return resource;
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}
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/*
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* Find an unused resource ID and return it. The first
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* VMCI_RESERVED_RESOURCE_ID_MAX are reserved so we start from
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* its value + 1.
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* Returns VMCI resource id on success, VMCI_INVALID_ID on failure.
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*/
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static u32 vmci_resource_find_id(u32 context_id,
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enum vmci_resource_type resource_type)
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{
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static u32 resource_id = VMCI_RESERVED_RESOURCE_ID_MAX + 1;
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u32 old_rid = resource_id;
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u32 current_rid;
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/*
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* Generate a unique resource ID. Keep on trying until we wrap around
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* in the RID space.
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*/
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do {
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struct vmci_handle handle;
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current_rid = resource_id;
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resource_id++;
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if (unlikely(resource_id == VMCI_INVALID_ID)) {
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/* Skip the reserved rids. */
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resource_id = VMCI_RESERVED_RESOURCE_ID_MAX + 1;
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}
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handle = vmci_make_handle(context_id, current_rid);
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if (!vmci_resource_lookup(handle, resource_type))
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return current_rid;
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} while (resource_id != old_rid);
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return VMCI_INVALID_ID;
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}
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int vmci_resource_add(struct vmci_resource *resource,
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enum vmci_resource_type resource_type,
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struct vmci_handle handle)
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{
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unsigned int idx;
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int result;
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spin_lock(&vmci_resource_table.lock);
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if (handle.resource == VMCI_INVALID_ID) {
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handle.resource = vmci_resource_find_id(handle.context,
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resource_type);
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if (handle.resource == VMCI_INVALID_ID) {
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result = VMCI_ERROR_NO_HANDLE;
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goto out;
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}
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} else if (vmci_resource_lookup(handle, resource_type)) {
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result = VMCI_ERROR_ALREADY_EXISTS;
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goto out;
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}
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resource->handle = handle;
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resource->type = resource_type;
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INIT_HLIST_NODE(&resource->node);
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kref_init(&resource->kref);
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init_completion(&resource->done);
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idx = vmci_resource_hash(resource->handle);
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hlist_add_head_rcu(&resource->node, &vmci_resource_table.entries[idx]);
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result = VMCI_SUCCESS;
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out:
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spin_unlock(&vmci_resource_table.lock);
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return result;
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}
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void vmci_resource_remove(struct vmci_resource *resource)
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{
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struct vmci_handle handle = resource->handle;
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unsigned int idx = vmci_resource_hash(handle);
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struct vmci_resource *r;
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struct hlist_node *node;
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/* Remove resource from hash table. */
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spin_lock(&vmci_resource_table.lock);
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hlist_for_each_entry(r, node, &vmci_resource_table.entries[idx], node) {
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if (vmci_handle_is_equal(r->handle, resource->handle)) {
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hlist_del_init_rcu(&r->node);
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break;
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}
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}
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spin_unlock(&vmci_resource_table.lock);
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synchronize_rcu();
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vmci_resource_put(resource);
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wait_for_completion(&resource->done);
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}
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struct vmci_resource *
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vmci_resource_by_handle(struct vmci_handle resource_handle,
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enum vmci_resource_type resource_type)
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{
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struct vmci_resource *r, *resource = NULL;
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rcu_read_lock();
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r = vmci_resource_lookup(resource_handle, resource_type);
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if (r &&
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(resource_type == r->type ||
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resource_type == VMCI_RESOURCE_TYPE_ANY)) {
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resource = vmci_resource_get(r);
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}
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rcu_read_unlock();
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return resource;
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}
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/*
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* Get a reference to given resource.
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*/
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struct vmci_resource *vmci_resource_get(struct vmci_resource *resource)
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{
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kref_get(&resource->kref);
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return resource;
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}
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static void vmci_release_resource(struct kref *kref)
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{
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struct vmci_resource *resource =
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container_of(kref, struct vmci_resource, kref);
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/* Verify the resource has been unlinked from hash table */
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WARN_ON(!hlist_unhashed(&resource->node));
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/* Signal that container of this resource can now be destroyed */
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complete(&resource->done);
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}
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/*
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* Resource's release function will get called if last reference.
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* If it is the last reference, then we are sure that nobody else
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* can increment the count again (it's gone from the resource hash
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* table), so there's no need for locking here.
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*/
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int vmci_resource_put(struct vmci_resource *resource)
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{
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/*
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* We propagate the information back to caller in case it wants to know
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* whether entry was freed.
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*/
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return kref_put(&resource->kref, vmci_release_resource) ?
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VMCI_SUCCESS_ENTRY_DEAD : VMCI_SUCCESS;
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}
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struct vmci_handle vmci_resource_handle(struct vmci_resource *resource)
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{
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return resource->handle;
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}

‎drivers/misc/vmw_vmci/vmci_resource.h‎

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/*
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* VMware VMCI Driver
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*
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* Copyright (C) 2012 VMware, Inc. All rights reserved.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the
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* Free Software Foundation version 2 and no later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*/
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#ifndef _VMCI_RESOURCE_H_
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#define _VMCI_RESOURCE_H_
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#include <linux/vmw_vmci_defs.h>
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#include <linux/types.h>
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#include "vmci_context.h"
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enum vmci_resource_type {
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VMCI_RESOURCE_TYPE_ANY,
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VMCI_RESOURCE_TYPE_API,
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VMCI_RESOURCE_TYPE_GROUP,
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VMCI_RESOURCE_TYPE_DATAGRAM,
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VMCI_RESOURCE_TYPE_DOORBELL,
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VMCI_RESOURCE_TYPE_QPAIR_GUEST,
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VMCI_RESOURCE_TYPE_QPAIR_HOST
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};
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struct vmci_resource {
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struct vmci_handle handle;
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enum vmci_resource_type type;
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struct hlist_node node;
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struct kref kref;
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struct completion done;
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};
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int vmci_resource_add(struct vmci_resource *resource,
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enum vmci_resource_type resource_type,
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struct vmci_handle handle);
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void vmci_resource_remove(struct vmci_resource *resource);
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struct vmci_resource *
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vmci_resource_by_handle(struct vmci_handle resource_handle,
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enum vmci_resource_type resource_type);
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struct vmci_resource *vmci_resource_get(struct vmci_resource *resource);
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int vmci_resource_put(struct vmci_resource *resource);
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struct vmci_handle vmci_resource_handle(struct vmci_resource *resource);
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#endif /* _VMCI_RESOURCE_H_ */

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